In JS, you know that library code that you call almost certainly won't do blocking I/O. If you're trying to do non-blocking async stuff in other languages, you

In JS, you know that library code that you call almost certainly won't do blocking I/O. If you're trying to do non-blocking async stuff in other languages, you have to hope/check that none of your code and none of your dependencies try to do blocking I/O. (Unless you're using something that does async under the covers like haskell or go)